WASHINGTON — In one corner we have Barack Obama, an African-American senator whose candidacy blossomed when white people saw him as capable of transcending America’s divisions — racial and otherwise. In the other corner is Hillary Clinton, senator and former first lady, who began the drive for the White House even more popular with black voters than Obama.

It was clear early on that the Democrats were destined to nominate either the first black or first woman for president. And if any two candidates seemed able to elude the snares of identity politics, these did.

But as it grinds its way into spring, the deadlocked campaign appears on the verge of becoming a bloody, knockdown-dragout racial brawl, pitting the likes of Geraldine Ferraro against Obama’s preacher, the Rev. Jeremiah Wright.

Americans aren’t good at talking about race under the best of circumstances. A presidential campaign may be the very worst, as partisans search not for truth, love or understanding, but for competitive advantage and the most sinister reading of each other’s words and actions.

On Tuesday, Obama will attempt to staunch the bleeding by delivering a major address on “race, politics and how we bring our country together at this important moment in our history,” at the National Constitution Center in Philadelphia.

This all holds special peril for Obama. This is because, to the extent that we retreat to racial corners, there are a lot more white voters than black. And it’s because the implicit appeal of Obama’s groundbreaking candidacy was that he could carry America beyond the ugliness now engulfing the Democrats.

“Ideally, the theory goes that bad speech leads to good speech — that when there is unproductive, damaging dialogue … entities who care about productive healing dialogue step in and nurture that,” said Susan Glisson, director of the William Winter Institute for Racial Reconciliation at Ole Miss.

Glisson, who is white, has worked to bring people together across racial lines under the most difficult conditions. But it is a long, painstaking process, conducted face to face in churches, classrooms and barbershops. She wouldn’t know where to begin amid a presidential race grounded in the gotcha of competing sound bites.

“Where’s the room for calm voices?” she asked.

Certainly not on the campaign conference calls or cable coverage feasting on Ferraro’s suggestions that, but for his black skin, Barack Obama would be a talented also-ran. Certainly not in bringing to the broader public the sermons of Jeremiah Wright, recently retired pastor of Obama’s church in Chicago, in which Wright condemns America and places Hillary Clinton in its white oligarchy.

You don’t have to be a diversity trainer to know such remarks are very differently received by black and white audiences. But Barry Cross Jr., who heads the Philadelphia diversity management firm founded by his mother, Elsie, knows better than most how easily this can spiral out of control.

“America is on the verge of rolling off that scary cliff,” said Cross, who worked on President Clinton’s race initiative. “We’re right on the ledge. The chasm is deep and maybe we can’t see the bottom.”

The truth about race in America, Cross said, is that people must accept that there is no single truth; there are only “multiple realities.” On the other hand, “the political process is right and wrong, it’s binary, there is no gray area.”

Consider that Cross, who is black, acknowledges that “part of what (Ferraro) was saying is true. Barack was in the right place and the time was right for a black man to captivate the country.”

But to many her words fit a predictable script — the white backlash against affirmative action. Hillary Clinton, the better qualified white candidate, was being passed over because America felt somehow obliged to give the job to a less qualified black man. Obama, Ferraro memorably insisted, was “lucky” to be black.

To some whites, she was telling it like it is. To some blacks, it was the same old insidious racism suggesting that no matter how talented a black person is, he owes his success to the color of his skin.

On Wednesday, Karol Collymore, a black woman blogging on BlueOregon, recalled how after working seven months on Al Gore’s campaign in 2000 in New Mexico, “a colleague said to me that I did a good job but did I know I was only hired by the party chairman because I was black?”

Now, she said, Ferraro, a childhood heroine, “brought this nasty memory to me again these past few days. It has haunted me since I heard it and it won’t go away. I’m going to tell you, it would have been less hurtful if the woman had just said the `n’ word.”

Instead Ferraro was back on TV, day after day, portraying herself as the victim of cynical, hysterical charges of racism, which, said Cross, probably strikes a responsive chord with “every white person who feels they have been accused of being a racist, or every man accused of being a sexist, when they felt they were just struggling to get through a conversation.”

Then came the YouTube videos of sermons by Wright, the fiery pastor emeritus of Trinity United Church of Christ on Chicago’s South Side. In them, Wright likens those “hatin’ on Barack Obama” to the enemies of Jesus, “a poor black man who lived in a country and who lived in a culture controlled by rich white people.”

Ignoring the possibility that being a woman might have presented Clinton with challenges in her rise, Wright identifies her as just another product of white privilege.

The angry performance resonates in black communities familiar with its tone and substance and sympathetic with the notion that a black person in America who is not at some level angry isn’t thinking hard enough. But it is the very antithesis of the Obama persona.

Obama has “put himself in a very tough position,” said Andra Gillespie, a political scientist at Emory University, who is black.

By settling on the South Side, marrying his wife, Michelle, and joining a popular Afrocentric church, Obama, whose mother was white, helped establish his bona fides in the black community. But now, the words of Wright — from whom Obama has distanced himself — give second thoughts to whites.

Obama was supposed to be the racially transcendent candidate, the black candidate who didn’t make them feel guilty for being white. How, Gillespie asked, does he break the news to them that his election “is not going to end the discussion of race in this country?”

For Obama supporters, the injection of race in the campaign has been almost entirely the work of the Clintons and their minions, determined to ghettoize Obama’s candidacy and reap the reward in states like Pennsylvania, where Gov. Ed Rendell, a Clinton supporter, said some whites were not ready to vote for a black candidate. (Some in Obama’s camp saw this as another play of the race card, but Cross thought Rendell ought to be congratulated for telling the truth.)

Meanwhile, on The New Republic’s Web site, Princeton historian and Clinton partisan Sean Wilentz sees Obama and his campaign as the racial provocateurs. Wilentz, who is white, called their tactics “the most outrageous deployment of racial politics since the Willie Horton ad campaign in 1988 and the most insidious since Ronald Reagan kicked off his 1980 campaign in Philadelphia, Mississippi, praising states’ rights.”

Where does it go from here?

To Cross, Obama is “damned if he does and damned if he doesn’t. Even if Obama told America that it is going to take a lot more hard work than electing him to get past race, that would be seen as pandering to black people.”

Who knows? said Glisson.

All eyes will be on Obama when he addresses the issue of race Tuesday in Philadelphia. Perhaps, Glisson said, “He could say there’s something even more important than who wins this election, and talk about the kind of country we want to have,” she said.

But it’s a very risky strategy, Glisson said; “It would take visionary cojones.”